Trypanosomes and trypanosomiasis / by A. Laveran and F. Mesnil. : Translated and much enlarged by David Nabarro.

  • Charles Louis Alphonse Laveran
Date:
1907
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Licence: In copyright

Credit: Trypanosomes and trypanosomiasis / by A. Laveran and F. Mesnil. : Translated and much enlarged by David Nabarro. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    Section 5.—Natural Modes of Infection in Rats. The natural infection in grey wild rats seems to be conveyed by means of fleas and lice, which, after sucking the blood of infected animals, bite healthy animals. On crushing lice caught on infected rats, we have found, in well-stained specimens of the stomach contents, absolutely normal trypanosomes amongst the red blood-corpuscles. [McNeaP has . also found trypanosomes in lic^ fed on infected animals; and in one experiment such lice infected a healthy rat- He was unable to make out any developmental stages in the lice. Prowazek's^ observa- tions are very interesting and important, because he was able not only to distinguish trypanosomes in various stages in the body of a rat-louse [Hmnatopinus spinulosus), but also to observe the formation of sexual forms, as will be described more in detail later. From these experiments of Prowazek it seems to follow that the Hcemato- pinus is a true alternate or definitive host, and not merely a mechanical carrier of the parasite. This is the first time that a sexual cycle of development in a mammalian trypanosome has been observed.] Sivori and Lecler have found living T. lewisi in fleas. Rabino- witsch and Kempner did not succeed in finding trypanosomes in fleas caught on infected rats, but when they crushed some of these insects in salt solution, and inoculated the mixture into the peritoneal cavity of healthy rats, an infection occurred in five out of nine cases. Sivori and .Lecler have successfully repeated this experiment. Rabinowitsch and Kempner have, in addition, made the following observations : 1. An infected white rat was kept together with healthy rats. At the end of eleven to fifteen days trypanosomes appeared in the blood of the healthy animals. (Sivori and Lecler and we ourselves have confirmed this observation.) 2. About twenty fleas caught on infected rats were placed upon a healthy rat. At the end of two to three weeks trypanosomes appeared in its blood*. These experiments tend to show that fleas play a part in the transmission of T. lewisi analogous to that of the tsetse-fly in the transmission of nagana. The transmission by fleas and lice, which are apterous insects, explains why the infection in rats in any particular locality may be very localized ; for example, the loft in Ann Arbor where McNeal and Novy found all the rats infected. Attempts to produce infection by the mouth or stomach have given negative results with all observers except Francis {vide supra). It is certain that rats may become infected by eating food mixed with blood containing trypanosomes or by devouring infected rats, but only when there is an abrasion of the muzzle or buccal mucous y'^^^^^ I McNeal,Infec. Dis., v. i, 1904, pp. 517-543.] 2 [Prowazek, Ard. a. d. kaiscrl. Gcsund., v. 22, 1905.]